The present disclosure relates to contrast media used in imaging procedures, such as magnetic resonance (MR), computed tomography (CT) imaging, and X-ray imaging. Contrast media is a radiopaque substance used in radiography to enhance the contrast of structures or fluids within the body to permit medical imaging. When contrast media is introduced into a patient, for example, into a patient's vasculature, it clarifies the anatomy to imaging devices and enables more detailed radiographic images. During imaging, contrast media enables body structures through which the contrast media flows, particularly blood vessels and the gastrointestinal tract, to be visibly distinguished in the resulting image. Common intravascular contrast media fluids include iodine based, or gadolinium based solutions.
Some diagnostic imaging procedures required the infusion of large quantities of contrast media into a patient infused at very high speeds. For example, some diagnostic imaging procedures utilize contrast media to improve lesion conspicuity in an effort to increase early diagnostic yield. Such a procedure necessitates viscous contrast media to be injected by a specialized “power injector” pump intravenously at very high flow rates, which establishes a contrast bolus or small plug of contrast media in the blood stream of the patient which results in enhanced image quality. The speed of these infusions combined with the viscosity of the contrast media fluids can cause damage to the patient's vasculature.
To establish a contrast bolus or small plug of contrast media in the bloodstream of the patient, the viscous contrast media is injected by a specialized “power injector” pump intravenously at very high flow rates. Power injection procedures generate high pressures within the infusion system, thereby requiring specialized vascular access devices, extension sets, media transfer set, pump syringes, and bulk or pre-filled contrast media syringes. As the concentration (and thereby viscosity) and infusion rate of the contrast media are increased, bolus density also increases resulting in better image quality via computed tomography (CT) attenuation. Therefore, a current trend in healthcare is to increase the bolus density of the contrast media by increasing both the concentration of the contrast media and the rate at which the media is infused into the patient, all of which ultimately drives system pressure requirements higher.
Intravenous infusion rates may be defined as either routine, generally up to 999 cubic centimeters per hour (cc/hr), or rapid, generally between about 999 cc/hr and 90,000 cc/hr (1.5 liters per minute) or higher. For some diagnostic procedures utilizing viscous contrast media, an injection rate of about 1 to 10 ml/second is needed to ensure sufficient bolus concentration. Power injections of viscous media at this injection rate produce significant complications as a result of the high pressures involved. The complications are caused by the combination of the high speed injections and the high fluid viscosity causes of contrast media.
While it is known that contrast media should preferably be heated prior to administration, clinical observations reveal that medical personnel generally do not administer heated contrast media during imaging procedures. This phenomenon is generally caused by medical personnel's failure to preheat the contrast media or a failure to maintain the contrast media at a preheated temperature before and during use. Preheating the contrast media allows for a more comfortable infusion to the patient, as well as a reduction in fluid viscosity, which may decrease the occurrence of complications. Studies have found that the viscosity of some contrast media is reduced by approximately 50% when the media is preheated from 22 degrees Celsius to 35 degrees Celsius. This dramatic decrease in viscosity can produce significantly fewer procedural complications during high speed injections.
Clinical observations have also revealed that the specific reasons for not administering heated contrast media are generally two-fold. First, regulations from medical accreditation bodies, such as the Joint Commission Accreditation body (JCAHO), strictly regulate medicaments that are heated, requiring detailed logs, records, and container tracking. Additionally, under some the regulations, some unused medicaments must be discarded after a certain lapse of time, such as twenty-four hours after being heated. These regulations are sufficiently burdensome that some medical personnel forego heating the contrast media in order to avoid the JACHO requirements. Thus, the understood benefits of preheating contrast media are not realized because it is practically too difficult to repeatedly measure and record the contrast media temperature; track the specific contrast media containers; and continually reheat the contrast media once it has begun to cool down.
The second reason for failure to administer heated contrast media is the natural delays involved in imaging during which time heated contrast media is allowed to cool. Imaging procedures required setting up the imaging device, which generally includes coupling the contrast media to the imaging device, and then conducting several imaging sessions. Generally, the contrast media is only heated prior to the first imaging session, during which time it cools before it is used for subsequent imaging sessions. For example, it is common for contrast media to be contained in 0.5 liter containers. These large containers provide contrast for multiple imaging sessions, such as three to five discrete sessions. However, prior to or during of the first imaging session, the contrast media cools to room temperature. Accordingly, subsequent imaging patients receive doses of room temperature infusions of contrast media which has a much higher viscosity and tends to be less comfortable to the patient.
Accordingly, there is a long-felt need in the art for solutions to the problem of contrast media heating and temperature maintenance. Such solutions are disclosed herein.